In plane switching liquid crystal displaying apparatus for improving luminance

ABSTRACT

An IPS liquid crystal displaying apparatus includes: a TFT array substrate, an opposite substrate opposed to the TFT array substrate and liquid crystal interposed between the TFT array substrate and the opposite substrate, wherein the TFT array substrate is composed of a glass substrate, a gate insulating film formed on the glass substrate, a possivation film formed on the gate insulating film, a plurality of scanning lines for transmitting a scanning signal, a plurality of signal lines for transmitting an image signal, a plurality of pixels arranged in grid like pattern by crossing the plurality of scanning lines with the plurality of signal lines, a plurality of TFTs implementing switching operation of the image signal on the basis of the scanning signals, a plurality of driving electrodes connected with the TFT, a plurality of opposite electrodes arranged in such a manner that each of the plurality of opposite electrodes is opposed to each of the driving electrodes, and a plurality of common lines for mutually connecting each of the opposite electrode of one of the plurality of pixels with the other one of the plurality of pixels, wherein the TFT array substrate is formed on the passivation film, the passivation film being different from a layer provided with the driving electrode and the opposite electrode.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an IPS (In Plain Switching)liquid crystal displaying apparatus by generating an electric fieldparallel to an array substrate to drive the liquid crystal. Moreparticularly, the present invention relates to a construction of ahighly bright liquid crystal displaying apparatus increased in apertureratio by reducing influences of the leakage of electric field from asignal line, thereby reducing the light shielding area.

[0002] In an active matrix type liquid crystal displaying apparatus, anIPS system where the direction of the electric field to be applied onthe liquid crystal is made parallel to the array substrate is mainlyused as a method of obtaining a wider viewing angle (for example, seeJapanese Unexamined Patent Publication No. 254712/1996). It is reportedthat this system enables to remove the almost all of the change in thecontrast and the inversion of the gradation level in changing theviewing-angle direction (see, for example, AsiaDisplay, 95, page, 577 to580 by M. Oh-e, and others).

[0003] A construction of one pixel of the conventional IPS liquidcrystal displaying apparatus is depicted in FIGS. 43a and 43 b. FIG. 43ais the plain view thereof. FIG. 43b is a sectional view taken along aline A-A of FIG. 43a FIG. 44 is a circuit diagram showing an equivalentcircuit of one pixel of the pixel electrode of an IPS liquid crystaldisplaying apparatus. FIG. 45 is a circuit diagram for illustrating thecircuit of the IPS liquid crystal displaying apparatus. Referring toFIGS. 43a and 43 b:, reference numeral 1 denotes a glass substrate,numeral 2 denotes a scanning line, numeral 3 denotes a signal line,numeral 4 denotes a thin film transistor (TFT), numeral 5 denotes adriving electrode, numeral 6 denotes an opposite electrode, numeral 7denotes an electrode for forming the storage capacitance, numeral 8denotes common line, numeral 9 denotes a gate insulating film, numeral10 denotes a passivation film, numeral 11 denotes a liquid crystal,numeral 12 denotes a BM (black matrix), numeral 14 denotes a contacthole, numeral 15 denotes a source electrode, and numeral 16 denotes adrain electrode. Numeral 20 denotes an array substrate comprising glass;substrate 1, a signal line 3, a driving electrode 5, an oppositeelectrode 6. Numeral 30 denotes an opposite substrate arranged oppositeto the array substrate 20. Numeral 40 denotes a slit which is a gapbetween the signal line 3 and the opposite electrode 6, and numeral 50denotes an opening. Referring to FIG. 44 and FIG. 45, the same referencenumerals as those of FIGS. 43a and 43 b depict the same parts or itsequivalents as those of FIGS. 43a and 43 b.

[0004] The construction and operation of the conventional IPS liquidcrystal displaying apparatus will be described according to FIGS. 43aand 43 b, FIG. 44 and FIG. 45. Referring to FIG. 45, a plurality of gridshaped pixels encircled by the scanning line 2 and the signal line 3 canbe made by crossing, at an approximately right angle between a scanningline 2 connecting the scanning line driving circuit 102 and a signalline 3 connecting the signal line driving circuit 101. A TFT (Thin FilmTransistor) is provided at each intersection point between a signal lineand a scanning line for forming the grid shaped pixel. Numeral 103denotes a circuit for common lines.

[0005] This condition is shown by an equivalent circuit in FIG. 44. TheTFT 4 is a semiconductor element having three electrodes of a gateelectrode, a source electrode 15 and a drain electrode 16. The gateelectrode is connected with a scanning line 2 extended from the scanningline driving circuit. The source electrode 15 is connected with thesignal line 3 connected with the signal line driving circuit. Theremaining drain electrode 16, connected with the driving electrode 5,drives the liquid crystal by an electric field caused between thedriving electrode 5 and the opposite electrode 6. Numeral 13 denotes astorage capacitance for storing the electric charge between the drivingelectrode 5 and the opposite electrode 6. The construction of one pixelwill be described in accordance with FIG. 43a and FIG. 43b. In a pixelformed through the crossing between the scanning line 2 and the signalline 3 are provided a driving electrode 5 for driving the liquid crystallayer, an opposite electrode 6 and a TFT 4. In the TFT 4 there are threeelectrodes. The scanning line 2 connected with the scanning line drivingcircuit shown in FIG. 45 is connected with the gate electrode of the TFT4, so as to apply the scanning signal, the scanning line driving circuitoutputs, upon the gate electrode of the TFT 4.

[0006] The signal line 3 connected with the signal line driving circuitis connected with the source electrode 15 of the TFT 4 to transmit theimage signal the signal line driving circuit outputs. The drainelectrode 16 of the TFT 4 is connected with the driving electrode 5through a contact hole 14 as shown in FIG. 43a. In the same pixel, anopposite electrode 6 is provided to be engaged face to face with thedriving electrode 5. The opposite electrode 6 is connected with thecommon line 8. The common line 8 is connected with each oppositeelectrode 6 provided in each pixel on the TFT array substrate 20.

[0007] The sectional construction of the picture section will bedescribed in accordance with FIG. 43b. A driving electrode 5 and anopposite electrode 6 are respectively formed on the glass substrate 1.Although not shown in FIG. 43b, the scanning line 2 and the common line8 are also formed in the same layer as that of the driving electrode 5and the opposite electrode 6. The gate insulating film 9 is laminated ona glass substrate by covering the driving electrode, the oppositeelectrode, the scanning line and the common line, and the signal line 3is formed on the gate insulating film 9. Although not shown in FIG. 43b,the storage capacitance forming electrode 7 is also formed in the samelayer as that of the signal line: 3. A passivation film 10 is laminatedfurther on the signal line 3, so as to form the TFT array substrate 20.The TFT array substrate 20 and the opposite substrate 30 is superposed.The IPS liquid crystal displaying apparatus is made with a liquidcrystal 11 being sealed between the TFT array substrate 20 and theopposite substrate 30.

[0008] The IPS liquid crystal displaying apparatus is a system where theelectric filed is caused along the surface of the TFT array substrate 20between the driving electrode 5 and the opposite electrode 6 provided onthe TFT array substrate 20. Thus, the opposite substrate 30 is ano-electrode substrate having no electrode. On the opposite substrate 30there is provided a BM 12 which is a light shielding film. Although notshown, the light leaked from a slit 40 of FIG. 43a is to be shieldedwith a back light, provided on the under side of the TFT arraysubstrate, as a light source in FIG. 43b.

[0009] An area surrounded by broken lines shown by 50, defining anopening per pixel, functions as a role of a window through which lightpasses with the back light as a light source. But the light from theback light is shielded by a driving electrode 5, an opposite electrode6, a black matrix 12 and so on, thereby influencing upon the picturequality of the liquid crystal display. Thus, a problem is to reduce theratio, in area, of the driving electrode 5, the opposite electrode 6,the black matrix 12 and so on to be occupied in the area of the opening50.

[0010] The above description is given about the construction of thepixel of the conventional IPS liquid crystal displaying apparatus aboutFIGS. 43a and 43 b, FIG. 44 and FIG. 45. The operation of the IPS liquidcrystal displaying apparatus will be described. The gate electrode isprovided in each pixel. The gate electrode of the TFT is connected withthe scanning line 2. The source electrode 15 is connected with thesignal line 3. The drain electrode 16 is connected with the drivingelectrode 5. Such a TFT 4 is a semiconductor switching element, whichcontrols the driving operation of the liquid crystal of each pixel. Whena scanning signal is applied, through the scanning line 2 from thescanning line driving circuit, upon the gate electrode of the TFT 4, allthe TFT 4 of this horizontal line is respectively switched on.

[0011] When the gate electrode is switched on, the image signaltransmitted from the signal line driving circuit flows to the drainelectrode 16 by way of the source electrode 15 and is stored in thedriving electrode 5 connected with the drain electrode 16. Electriccharge applied in the driving electrode 5 is stored with respect to theopposite electrode 6 and the gate electrode is turned on again. Theelectric charge of that time is stored before the new image signalelectric charge is applied. The driving electrode 5 and the oppositeelectrode 6 function as a capacitor in that the electric charge isstored while the gate electrode is on, and the stored electric charge isheld as it is when the gate electrode is turned off. The storagecapacitance 13 shown in FIG. 44 increases the accumulating force of thecapacitance. The storage capacitance 13 is formed by the verticallamination of the storage capacitance electrode 7 and the common line 8through the gate insulating film 9.

[0012] In the conventional IPS liquid crystal displaying apparatus shownin FIGS. 43a and 43 b, between the signal line 3 provided in the sideend portion of one pixel and the opposite electrode 6 formed in parallelto the signal line 3 is caused an electric field due to the potentialdifference between the signal line 3 and the opposite electrode 6. FIG.46 is a view showing influences to be applied, upon the electric fieldto be caused between the driving electrode 5 and the opposite electrode6, by the electric field caused between the signal line 3 and theopposite electrode 6 of the conventional IPS liquid crystal displayingapparatus, which has the TFT array substrate where the driving electrode5 and the opposite electrode 6 are formed in the layer lower than thesignal line 3. In FIG. 46, changes in the potential caused between thedriving electrode 5 and the opposite electrode 6 is obtained as asimulator.

[0013] In FIG. 46, the electric potential in the window upper portion orlower portion is calculated when a white window has been displayed inthe half tone of the relative transmission factor 50 %.

[0014] It is desirable to correctly drive the liquid crystal to have thedriving electrode 5 between two opposite electrodes 6 so that thepotential distribution is symmetrical around the driving electrode 5. Itis found out from FIG. 46 that the potential distribution of an areanear the signal line 3 of the opening 50 is subjected to the influencesof the leakage of electric field caused between the signal line 3 andthe opposite electrode 6, thus resulting in asymmetric potentialdistribution. The electric field is caused along the surface of theglass substrate 1, thus causing a problem like crosstalk. For example,when a white window is displayed in such black displaying as shown inFIG. 47, there prises a problem on the display called “longitudinalcrosstalk” where the vertical luminance of the window portion changeswith respect to the other black displaying portion.

[0015] An example in a case of a normally black mode (wherein thedisplaying becomes black with the voltage being not applied) will bedescribed in FIG. 44. When such a window pattern in FIG. 47 isdisplayed, the same voltage as that: of the opposite electrode 6 isapplied during the selecting period of the black displaying portion 111upon the signal line 3 of the pixels of the window and its upper andlower portions during the picture face, and a voltage necessary to thewhite displaying 113 is applied during the selecting period of the whitedisplaying portion 111.

[0016] The voltage of a value where the absolute value of the electricpotential value between the electrodes has been averaged by hour isapplied upon the liquid crystal 11 effectively. Therefore, for example,when the black displaying and the white displaying are equal in theselecting period, the effective potential equal to the half tone display112 is applied upon these pixels between the signal line 3 and theopposite electrode 6. At this time, the liquid crystal on the slit 40between the signal line 3 and the opposite electrode 6 becomes atransmission mode by the electric field to horizontal to the glasssubstrate 1 to be caused between the signal line 3 and the oppositeelectrode 6. The electric field to be caused by the electrical potentialdifference between the signal line 3 and the opposite electrode 6 givesinfluences even upon the electric field between the driving electrode 5and the opposite electrode 6, so as to change the liquid crystal of theblack displaying portion into the transmission mode. As a result, thecrosstalk is caused.

[0017] In order to prevent such longitudinal crosstalk from beingcaused, the leaking light transmitting through the slit 40 between thesignal line 3 and the opposite electrode 6 is required to be shielded bythe BM 12 formed on the opposite substrate 30 and to prevent theelectric field, caused between the signal line 3 and the oppositeelectrode 6, from being interfered with the electric field between thedriving electrode 5 and the opposite electrode 6 with the drivingelectrode 5 and the opposite electrode 6 spaced apart from the oppositeelectrode 6 of the side end portion on the side of the opening 50, andthe signal line 3. When the driving electrode 5 and the oppositeelectrode 6 are separated from the signal line 3 to make larger thewidth of the opposite electrode 6 adjacent to the signal line 3, and theaperture ratio of the opening 50, namely, a portion to be occupied by anarea where the area of the driving electrode 5 and the oppositeelectrode 6 and so on is subtracted from the area of the opening 50 withrespect to the area of the opening 50 surrounded with broken lines inFIG. 43a, becomes smaller to make the picture quality worse. In order todevelop the high picture quality liquid crystal displaying apparatus, itis necessary to shield the light, without reducing the aperture ratio,the electric field to be caused between the signal line 3 and theopposite electrode 6 adjacent to the signal line 3.

[0018] As clear from FIG. 43b, level of the surface of the passivationfilm 10 which is an upper layer film of the array substrate 20 is notflat (level difference), and the gap between the surface of thepassivation film 10 and the opposite substrate 30 is not flat. Thus,uneven luminance is likely to be caused, causing the picture qualityworse. The level difference provided makes not only the array substrateinferior due to crack, but also disconnects the wiring on the arraysubstrate due to the level difference portion in the manufacturingoperation with a problem in improving the yield factor and reliabilityof the product.

[0019] Further, in accordance with the conventional IPS liquid crystaldisplaying apparatus, picture quality is deteriorated by light leakingtransmitted from the slit 40, the light being emitted by a back lightserving as a light sourse. In order to shield the leaked light, theblack matrix 12 is provided on the opposite substrate 30. However, whenthe TFT array substrate 20 is superposed with the opposite substrate 30,there might be generated error. Then, the black matrix 12 has beenformed in such a manner as to be somewhat larger with some margin forthe purpose of taking the error into consideration. However, therearises such a problem in which opening ratio is lowered when shiedingeffect is enhanced by making the black matrix 12 large.

[0020] The first object of the present invention is to solve theproblems mentioned above, and to provide an IPS liquid crystaldisplaying apparatus causing electric field parallel to a glasssubstrate, the IPS liquid crystal displaying apparatus capable ofimproving shielding effect against electric field leaking from thesignal line, making the opening wide (that is, making opening ratiohigh) by lowering the light shielding area. Further, the second objectof the present invention is to provide a high quality IPS liquid crystaldisplaying apparatus in which cost for producing the apparatur isdecreased by preventing the lines from disconnection thereby improvingthe yield factor.

SUMMARY OF THE INVENTION

[0021] The IPS liquid crystal displaying apparatus of the presentinvention comprises:

[0022] a TFT array substrate,

[0023] an opposite substrate opposed to the TFT array substrate and

[0024] liquid. crystal interposed between the TFT array substrate andthe opposite substrate,

[0025] wherein the TFT array substrate is composed of a glass substrate,a gate insulating film formed on the glass substrate, a possivation filmformed on the gate insulating film, a plurality of scanning lines fortransmitting a scanning signal, the plurality of scanning lines beingformed on the glass substrate, a plurality of signal lines fortransmitting an image signal, the plurality of signal lines being formedon the gate insulating film, a plurality of pixels arranged in grid likepattern by crossing the plurality of scanning lines with the pluralityof signal lines, a plurality of TFTs implementing switching operation ofthe image signal on the basis of the scanning signals, a plurality ofdriving electrodes connected with the TFT, a plurality of oppositeelectrodes arranged in such a manner that each of the plurality ofopposite electrodes is opposed to each of the driving electrodes, and aplurality of common lines for mutually connecting each of the oppositeelectrode of one of the plurality of pixels with the other one of theplurality of pixels,

[0026] wherein the TFT array substrate is formed on the passivationfilm, the passivation film being different from a layer provided withthe driving electrode and the opposite electrode.

[0027] The IPS liquid crystal displaying apparatus of the presentinvention is provided with a driving electrode for driving the liquidcrystal layer by causing the electric field parallel to the TFT arraysubstrate face, the driving electrode being connected with the TFT, andan opposite electrode connected with a common line. At least theopposite electrode has a TFT array substrate formed on the passivationfilm, different from a layer where the signal line is formed.

[0028] The IPS liquid crystal displaying apparatus of the presentinvention has a TFT array substrate having an opposite electrode formedto cover one portion of the signal line or all the portion of the signalline.

[0029] The IPS liquid crystal displaying apparatus of the presentinvention has a TFT array substrate having an opposite electrode formedto cover one portion of the scanning line or all the portion thereof,having at least an opposite electrode in a layer different from thescanning line.

[0030] The IPS displaying apparatus of the present invention has acommon line and a scanning line on the same layer, and a signal lineprovided on the gate insulating film.

[0031] The IPS liquid crystal displaying apparatus of the presentinvention has a TFT array substrate with the surface of the passivationfilm being approximately flat in shape.

[0032] The IPS liquid crystal displaying apparatus of the presentinvention has a light shielding means formed to have the signal line andthe opposite electrode superposed.

[0033] The IPS displaying apparatus of the present invention has a TFTarray substrate formed, to have for superposition in different layers, aTFT for switching the picture image signal in accordance with thescanning signal, a driving electrode for accumulating, while the switchof the TFT is off, the electric load stored when the switch of the TFTis on, and a storage capacitance increasing electrode for reinforcingthe capacitance of the driving electrode.

BRIEF EXPLANATION OF THE DRAWINGS

[0034]FIG. 1 is a sectional view showing the construction of one pixelof an IPS liquid crystal displaying apparatus of Embodiment 1 of thepresent invention;

[0035]FIG. 2 is a plain view showing the construction of one pixel of anIPS switching type liquid crystal displaying apparatus of Embodiment 1of the present invention;

[0036]FIGS. 3a and 3 b are a plain view and a sectional view showing theconstruction of one pixel of an IPS liquid crystal displaying apparatusof the embodiment 1 of the present invention;

[0037]FIGS. 4a, 4 b, 5 a, 5 b, 6 a, 6 b, 7 a, 7 b, 8 a and 8 b depict isa process flow of a TFT array substrate of an IPS liquid crystaldisplaying apparatus of Embodiment 1 of the present invention;

[0038]FIGS. 9a, 9 b, 10 a, 10 b, 11 a, 11 b, 12 a, 12 b, 13 a and 13 bdepict is another process flow of a TFT array substrate of an IPS liquidcrystal displaying apparatus of Embodiment 1 of the present invention;

[0039]FIGS. 14a, 14 b, 15 a, 15 b, 16 a, 16 b, 17 a, 17 b, 18 a and 18 bdepict is a still another process flow of a TFT array substrate of anIPS liquid crystal displaying apparatus of Embodiment 1 of the presentinvention;

[0040]FIGS. 19a and 19 b are a plain view and a sectional view showingthe construction of one pixel of an IPS liquid crystal displayingapparatus of Embodiment 2 of the present invention;

[0041]FIGS. 20a, 20 b, 21 a, 21 b, 22 a, 22 b, 23 a, 23 b, 24 a and 24 bdepict a process flow of a TFT array substrate of an IPS liquid crystaldisplaying apparatus of Embodiment 2 of the present invention;

[0042]FIGS. 25a and 25 b are a plain view and a sectional view showingthe construction of one pixel of an IPS liquid crystal displayingapparatus of Embodiment 3 of the present invention;

[0043]FIGS. 26a, 26 b, 27 a, 27 b, 28 a, 28 b, 29 a, 29 b, 30 a and 30 bdepict a process flow of a TFT array substrate of an IPS liquid crystaldisplaying apparatus of Embodiment 3 of the present invention;

[0044]FIGS. 31a and 31 b are a plain view and a sectional view showingthe construction of one pixel of an IPS liquid crystal displayingapparatus of Embodiment 4 of the present invention;

[0045]FIGS. 32a and 32 b are a plain view and a sectional view showingthe construction of one pixel of an IPS liquid crystal displayingapparatus of Embodiment 5 of the present invention;

[0046]FIG. 33 is a view showing the potential distribution when thedriving electrode and the opposite electrode are in a layer higher thanthe upper layer;

[0047]FIGS. 34a and 34 b are a plain view and a sectional view showingthe construction of one pixel of an IPS liquid crystal displayingapparatus of Embodiment 6 of the present invention;

[0048]FIGS. 35a and 35 b are a plain view and a sectional view showingthe construction of one pixel of an IPS liquid crystal displayingapparatus of Embodiment 7 of the present invention;

[0049]FIG. 36 is a sectional view showing the construction of one pixelof an IPS liquid crystal displaying apparatus of Embodiment 8 of thepresent invention;

[0050]FIGS. 37a, 37 b, 38 a, 38 b, 39 a, 39 b, 40 a, 40 b, 41 a, 41 b,42 a and 42 b depict a process flow of a TFT array substrate of an IPSliquid crystal displaying apparatus of Embodiment 9 of the presentinvention;

[0051]FIGS. 43a and 43 b are a plain view and a sectional view showingthe construction of one pixel of the conventional IPS liquid crystaldisplaying apparatus;

[0052]FIG. 44 shows an equivalent circuit of one pixel of theconventional IPS liquid crystal displaying apparatus;

[0053]FIG. 45 is a block diagram showing the construction of theconventional IPS liquid crystal displaying apparatus;

[0054]FIG. 46 is an explanatory view showing the electric potentialdistribution when the driving electrode and the opposite electrode arein a layer lower than the signal line; and

[0055]FIG. 47 an explanatory a view showing a crosstalk.

DETAILED DESCRIPTION OF THE INVENTION Embodiment 1

[0056] One embodiment of the present invention will be described inaccordance with drawings. The reference numerals in Embodiment 1 are thesame as those of the conventional reference numerals. FIG. 1 is asectional view showing the construction of one pixel of the IPS typeliquid crystal displaying apparatus in Embodiment 1 of the presentinvention. FIG. 2 is its plain view. FIG. 1 is a sectional view takenalong a line of A-A in FIG. 2. Referring to the drawing, referencenumeral 1 denotes a glass substrate, numeral 2 denotes a scanning line,numeral 3 denotes a signal line, numeral 4 denotes a TFT, numeral 5denotes a driving electrode, numeral 6 denotes an opposite electrode,numeral 7 denotes an electrode for forming the storage capacitance,numeral 8 denotes a common line, numeral 9 denotes a gate insulatingfilm, numeral 10 denotes a passivation film, numeral 11 denotes a liquidcrystal, numeral 12 denotes a BM, numeral 14 denotes a contact hole,numeral 15 denotes a source electrode of the transistor, and numeral 16denotes a drain electrode of the transistor. Numeral 20 denotes an arraysubstrate comprising a glass substrate 1, a signal line 3, a drivingelectrode 5, an opposite electrode 6. Numeral 30 denotes an oppositesubstrate cerving as a displaying picture face arranged opposite to thearray substrate 20. Numeral 40 denotes a slit which is a gap between thesignal line 3 and the opposite electrode 6. Numeral 50 denotes anopening of a pixel. FIG. 3 depicts the construction of one pixel of theIPS type liquid crystal displaying apparatus when a channel passivationTFT 21 which is one type of a TFT 4 is provided as a TFT to be used inthe IPS type liquid crystal displaying apparatus shown in FIG. 2. FIG.3a is its plain view. FIG. 3b is a sectional view.

[0057] The construction of the pixel of the IPS type liquid crystaldisplaying apparatus will be described in accordance with FIG. 1 andFIG. 2. Referring to the drawings, numeral 1 denotes a glass substratewith a scanning line 2 being formed on the glass substrate 1. A gateinsulating film 9 is laminated to cover the scanning line 2 and a signalline 3 is provided on the gate insulating film 9. A passivation film 10is laminated on the signal line 3. A driving electrode 5 and an oppositeelectrode 6 are provided on the passivation film 10. The TFT arraysubstrate 20 is made as described above. A substrate 30 which isprovided to be opposed to the TFT array substrate 20 is an oppositesubstrate for grasping a liquid crystal 11 with respect to the TFT arraysubstrate 20. The IPS liquid crystal displaying apparatus of the presentinvention causes an electric field along the surface of the TFT arraysubstrate, and thereby to drive the liquid crystal 11 by controlling thedirection of the electric field.

[0058]FIG. 2 is a plain view of an IPS liquid crystal displayingapparatus shown in FIG. 1. Referring to FIG. 2, numeral 2 denotes ascanning line and numeral 3 denotes a signal line. An area surrounded bythe scanning line 2 and the signal line 3 becomes one pixel. Numeral 4denotes a TFT provided in the intersection point between the scanningline 2 and the signal line 3. The gate electrode of three electrodeshaving the TFT 4 is connected with the scanning line 2, and the sourceelectrode 15 is connected with the signal line 3. The drain electrode 16of three electrodes having the TFT 4 is connected with the drivingelectrode 5 by a contact hole 14 in an upper layer through a passivationfilm 10 (not shown). An opposite electrode 6 which is provided oppositeto be engaged with the driving electrode 5 is connected with the commonline 8 of the same layer. The common line 8 not shown is connected withthe opposite electrode 6 of the other adjacent pixel. The drivingelectrode 5, the opposite electrode 6, and the common line 8 are formedat the same time in a layer upper than the signal line 3.

[0059] Numeral 7 denotes storage capacitance for keeping the potentialof the driving electrode 5. The opposite electrode 6 and the drainelectrode 16 are laminated vertically. Numeral 40 denotes a slit betweenthe signal line 3 and the opposite electrode 6. The BM 12 provided inthis opposite substrate 30 shown in FIG. 1 shields the leakage lightwhich transmits through the slit 40 with the back light as a lightsource. Numeral 50 denotes an opening. The larger the area of theopening becomes, the higher picture quality the liquid display canobtain. As the IPS liquid crystal displaying apparatus retains theelectric charge stored in the driving electrode 5 connected with thedrain electrode 16 of the TFT 4 and drives the liquid crystal 11 bycausing the electric field along the surface of the glass substrate 1,the opposite substrate 30 is a no-electrode substrate not provided withan electrode. One example of the process flow of the TFT array substratefor composing the pixel of the IPS liquid crystal displaying apparatusin Embodiment 1 will be described.

[0060]FIGS. 4a, 4 b, 5 a, 5 b, 6 a, 6 b, 7 a, 7 b, 8 a and 8 b depict aprocess flow of a TFT array substrate. FIGS. 9a, 9 b, 10 a, 10 b, 11 a,11 b, 12 a, 12 b, 13 a and 13 b depict another process flow of a TFTarray substrate. FIGS. 14a, 14 b, 15 a, 15 b, 16 a, 16 b, 17 a, 17 b, 18a and 18 b depict still another process flow of a TFT array substrate.The left-hand side views of FIG. 4a through FIG. 18a show the TFT arraysubstrate and the right-hand side views thereof show the terminalportions for embodying the scanning line 2 into the scanning linedriving circuit. Referring to FIGS. 4a, 4 b, 5 a, 5 b, 6 a, 6 b, 7 a, 7b, 8 a and 8 b a step 1 (FIGS. 4a and 4 b) forms a scanning line 2, ofapproximately 50 nm through 800 nm in film thickness, under theconstruction of any one of Cr, Al, Mo, Ta, Cu, Al—Cu, Al—Si—Cu, Ti, W,or of their alloy, or transparent materials such as ITO (Indium TinOxide) or the like or the laminated thereof. The scanning line 2functions even as the gate electrode of the TFT 4. As an etching methodin forming the scanning line 2 may be used an etching method as thesection becomes rectangular although the taper etching which becomestrapezoidal in section is shown in FIGS. 4a, 4 b, 5 a, 5 b, 6 a, 6 b, 7a, 7 b, 8 a and 8 b.

[0061] In step 2 (FIGS. 5a and 5 b), a gate insulating film 9 isaccumulated to cover the scanning line 2, amorphous silicon withimpurities such as amorphous silicon, phosphorus and so on being dopedin it is continuously accommodated, then amorphous silicon is patternedand the TFT 4 is formed with a channel etch type. A gate insulating film9 is proper to have approximately 200 nm through 600 nm in thickness byusing a transparent insulating film such as silicon nitride, siliconoxide or the like, film oxide of a gate electrode material (namely, amaterial of the scanning line 2) or their laminated films. Also, a microcrystal silicon with impurities such as phosphorus or the like beingdoped in it can be used as a material instead of amorphous silicon withimpurities such as phosphorus or the like being doped in it.

[0062] In step 3 (FIGS. 6a and 6 b) there is formeds a signal line 3simultaneously with a source electrode 15 and a drain electrode 16 ofthe TFT 4. The signal line 3 functions as a source electrode 15. Thesignal line 3 is formed of any one of Cr, Al, Mo, Ta, Cu, Al—Cu,Al—Si—Cu, Ti, W or alloy mainly made of them, or alloy made chiefly ofthem, or a transparent material of such as ITO or the like or theirlaminated construction.

[0063] In step 4 (FIGS. 7a and 7 b) there is formed a passivation film.10 with a transparent insulating film of silicon nitride, silicon oxideand so on. In order to electrically connect the driving electrode 5 withthe drain electrode 16, the partial passivation film on the drainelectrode 16 of the TFT 4 is removed to form a contact hole 14. At thistime, the gate insulating film 9 and the passivation film 10 are removedfrom the terminal portion of the scanning line 2 at the same time andthe passivation film 10 is removed from the terminal portion of thesignal line 3 so that the external terminal, the scanning line 2 and thesignal line 3 can be connected electrically.

[0064] In step 5 (FIGS. 8a and 8 b) there is formed the drivingelectrode 5 and the opposite electrode 6, as an electrode for formingthe electric field in a horizontal direction to the substrate face, withany one of Cr, Al, Mo, Ta, Cu, Al—Cu, Al—Si—Cu, Ti, W or alloy mainlycomposed of at least two thereof, or a transparent material of such asITO or the like or their laminated construction or their laminatedconstruction including them. The driving electrode 5 is connected withthe drain electrode 16 through the contact hole 14. The oppositeelectrode 6 is connected with the common line 8. The opposite electrodes6 are superposed through the drain electrode 16 and the passivation film10 to form the storage capacitance 7 for keeping the electric potentialof the driving electrode. By the above five steps, the driving electrode5 and the opposite electrode 6 are provided in the layer (namely, on theside of the opposite substrate 30) upper than the signal line 3. The TFTarray substrate 20 which can apply the horizontal electric field to thesubstrate face can be made by using a channel etch type TFT with fivephoto-lithography processes.

[0065] Although the terminal 22 is formed by using the metal of the samelayer as that of the scanning line 2 in the process flow of the abovedescribed TFT array substrate, a terminal can be formed by using theITO. The ITO has only to be made of the same layer as that of thescanning line or the signal line 3. Although the signal wiring has beenstraightly etched, it is desirable to conduct a taper etching operation.When the signal line is formed on Cr under the Al laminatedconstruction, an over etching operation is conducted in Cr when the Crhas been patterned after the Al is patterned, the construction becomesprotective in construction, causing disconnection In order to preventit, the etching of Al is conducted again after the patterning of the Cr.Retreat the Al from the Cr end face and the protecting construction canbe prevented. This etching of the Al can use the taper etching. Thismethod can be adapted when the signal line is formed under the laminatedconstruction of different metals of two types or more of any one of Cr,Al, Mo, Ta, Cu, Al—Cu, Al—Si—Cu, Ti, W or alloy mainly composed of atleast two thereof, or transparent materials such as ITO or theirlaminated construction.

[0066] In FIGS. 4a, 4 b, 5 a, 5 b, 6 a, 6 b, 7 a, 7 b, 8 a and 8 b thedriving electrode 5 and the opposite electrode 6 can be formed on thesame layer and the driving electrode 5 and the signal line 3 are formedat the same time as shown in FIGS. 9a, 9 b, 10 a, 10 b, 11 a, 11 b, 12a, 12 b, 13 a and 13 b. After forming the passivation film 10 by usingthe silicon nitride or the like, the opposite electrode 6 can be formed.In this case, the driving electrode 5 and the opposite electrode 6 areformed in a separate layer. A channel passivation film transistor 21which is one type of TFT 4 can be used, instead of a TFT used for theTFT array substrate shown in FIGS. 4a, 4 b, 5 a, 5 b, 6 a, 6 b, 7 a, 7b, 8 a and 8 b. FIGS. 14a, 14 b, 15 a, 15 b, 16 a, 16 b, 17 a, 17 b, 18a and 18 b are views showing a process flow of the TFT array substrateformed by using a channel passivation film transistor 21.

[0067] The TFT array substrate shown in FIGS. 14a, 14 b, 15 a, 15 b, 16a, 16 b, 17 a, 17 b, 18 a and 18 b includes a pixel of the IPS liquidcrystal displaying apparatus shown in FIG. 3, and is formed much more inbranch layer than the TFT array substrate shown in FIG. 5. This is dueto the difference of a producing step (FIGS. 15a and 15 b) of forming ascanning line 2, then the continuously depositing the gate insulatingfilm 9, the amorphous silicon, and the channel passivation film to coverthe scanning line 2, then forming the channel passivation film 21,ion-injecting the impurities such as P and so on into the amorphoussilicon with the channel passivation film 21 as a mask to form ann-layer, and forming the channel passivation film transistor.

[0068] In the characteristic construction of the TFT array substrate 20of the IPS liquid crystal displaying apparatus of Embodiment 1, thedriving electrode 5 and the opposite electrode 6 on the array substrate20 are arranged on a layer (namely, on the side of the oppositesubstrate 30) upper than the signal line 3. This arrangement allows astep of forming the contact hole 14 and removing the passivation film 10from the terminal portion of the signal line 3, and a step of removingthe insulating film 9 and the passivation film 10 from the terminalportion of the scanning line 2 to carry out at one time. Thus, thenumber of the masks can be reduced by one and thereby the manufacturingcost can be reduced.

[0069] It has been found by forming the driving electrode 5 and theopposite electrode 6 on the layer of the side of the opposite substrate30 with the signal line 3 and the layer being made different that theinfluences of the electric field caused by the electric potentialdifference between the opposite electrode 6, provided adjacently to thesignal line 3 on the end portion of the opening 50 shown in FIG. 2, andthe signal line 3, as judged from the description to be mentioned laterin Embodiment 5. Thus, the opposite electrode of the side end portion ofthe opening 50 can be made closer to the signal line 3 and the area ofthe opening 50 can be made larger.

[0070] In FIG. 1, the driving electrode 5 and the opposite electrode 6are directly in contact with the liquid crystal interposed between theTFT array substrate 20 and the opposite substrate 30, so that the liquidcrystal can be efficiently driven, and the space between the drivingelectrode 5 and the opposite electrode 6 can be made wider. Thus, aneffect of improving the aperture ratio can be obtained.

Embodiment 2

[0071]FIGS. 19a and 19 b show the construction of the pixel electrode ofthe liquid crystal displaying apparatus of the embodiment 2 of thepresent invention. FIG. 19a is its plain view. FIG. 19b is a sectionalview taken along a line of A-A of FIG. 19a. FIGS. 20a, 20 b, 21 a, 21 b,22 a, 22 b, 23 a, 23 b, 24 a and 24 b are views showing the process flowof the array substrate. Referring to the drawing, reference numeral 1denotes a glass substrate, numeral 2 denotes a scanning line, numeral 3denotes a signal line, numeral 4 denotes a thin film transistor (TFT),numeral 5 denotes a driving electrode, numeral 6 denotes an oppositeelectrode, numeral 7 denotes an electrode for forming the storagecapacitance, numeral 8 denotes common line, numeral 9 denotes a gateinsulating film, numeral 10 denotes a passivation film, numeral 11denotes a liquid crystal, numeral 12 denotes a BM, numeral 14 denotes acontact hole, numeral 15 denotes a source electrode of a transistor, andnumeral 16 denotes a drain electrode. Numeral 18 denotes a through-hole,numeral 20 denotes an array substrate comprising a glass substrate 1, asignal line 3, a driving electrode 5, an opposite electrode 6. Numeral30 denotes an opposite substrate serving as a display picture facearranged opposite to the array substrate 20. Numeral 40 denotes a slitwhich is a gap between the signal line 3 and the opposite electrode 6.Numeral 50 denotes an opening of the pixel.

[0072] In Embodiment 1, the common line 8 is formed on the same layer asthat of the opposite electrode 6. In the embodiment 2, the common line 8is formed on the same layer as that of the scanning line 2, namely, onthe glass substrate 1 as shown in FIGS. 20a, 20 b, 21 a, 21 b, 22 a, 22b, 23 a, 23 b, 24 a and 24 b. The source electrode 15 is connected withthe signal line 3, which is laminated on the scanning line 2 and thecommon line 8 through the gate insulating film 9. Furthermore, thedriving electrode 5 and the opposite electrode 6 are formed through thepassivation film 10. The driving electrode 5 is connected with the drainelectrode 16 through the contact hole 14. The opposite electrode 6 isconnected with the common line 8 through the through-hole 18. Thechannel passivation film TFT can be used as the TFT 4.

[0073] In the IPS liquid crystal displaying apparatus of Embodiment 2,as in Embodiment 1, the driving electrode 5 and the opposite electrode 6are formed in a layer close to the liquid crystal different from thesignal line 3. As the liquid crystal can be driven more efficiently, thespace between the driving electrode 5 and the opposite electrode 6 canbe made wider to improve the aperture ratio. Since the common line 8 andthe scanning line 2 are formed in the same layer, the common line 8 canbe formed on the flat glass substrate 1 together with the scanning line2. Thus, a problem of disconnecting the common line 8 with a leveldifference portion is prevented from being caused, so as to improvetraction defective. Therefore, the reliability of the product isimproved. In Embodiment 1, the opposite electrode 6 cannot be madethinner in film due to resistivity of the common line 8, but inEmbodiment 2, the film of the opposite electrode 6 can be made thinner.The dispersion of the electrode space is made smaller due to the thinnerfilm of the opposite electrode 6, so as to realize a liquid crystaldisplaying apparatus which is less in uneven luminance across the wholepicture face.

Embodiment 3

[0074]FIGS. 25a and 25 b show the construction of one pixel of theliquid crystal displaying apparatus of the embodiment 2 of the presentinvention. FIG. 25a is its plain view. FIG. 25b is a sectional viewtaken along a line of A-A of FIG. 25a. FIGS. 26a, 26 b, 27 a, 27 b, 28a, 28 b, 29 a, 29 b, 30 a and 30 b are views showing the process flow ofthe array substrate. Referring to the drawing, reference numeral 1denotes a glass substrate, numeral 2 denotes a scanning line, numeral 3denotes a signal line, numeral 4 denotes a TFT, numeral 5 denotes adriving electrode, numeral 6 denotes an opposite electrode, numeral 7denotes an electrode for forming the storage capacitance, numeral 8denotes common line, numeral 9 denotes a gate insulating film, numeral10 denotes a passivation film, numeral 11 denotes a liquid crystal,numeral 12 denotes a BM, numeral 14 denotes a contact hole, numeral 15denotes a source electrode of a transistor, and numeral 16 denotes adrain electrode. Numeral 20 denotes an array substrate comprising aglass substrate 1, a signal line 3, a driving electrode 5, an oppositeelectrode 6. Numeral 30 is an opposite substrate serving as a displayingpicture face arranged opposite to the array substrate 20. Numeral 40denotes a slit which is a gap between the signal line 3 and the oppositeelectrode 6. Numeral 50 denotes an opening of the pixel.

[0075] In forming the TFT array substrate 20, the passivation film 10 isformed of a transparent insulation film such as silicon nitride, siliconoxide. The surface of the passivation film 10 is not flat and has alevel difference. In Embodiment 3, the passivation film 10 is made flatby removing the level difference of the surface of the passivation film10, as shown in FIG. 25b and FIGS. 26a, 26 b, 27 a, 27 b, 28 a, 28 b, 29a, 29 b, 30 a and 30 b, by forming with the use of a material such asacrylic melamine, acrylic epoxy or the like having a function offlattening the surface of the layer to be formed.

[0076] The IPS liquid crystal displaying apparatus of Embodiment 3 canequally constitute with precision the gap between the surface of thearray substrate across the whole displaying picture face and theopposite substrate 30 by flattening the surface of the passivation film10. A liquid crystal displaying apparatus which is less in unevenbrilliance across the whole picture face can be made. The fractiondefective which is caused due to cracks or the like in the leveldifference portion of the passivation film 10 can be made smaller toimprove the yield. A high quality liquid crystal displaying apparatuscan be realized which is applied equally in rubbing treatment necessaryto the orientation of the liquid crystal by the flattening operation andis less in orientation disturbing.

[0077] As in Embodiment 1, the driving electrode 5 and the oppositeelectrode 6 are provided closer to the liquid crystal than a formedlayer of the signal line 3, with an effect of improving the apertureratio, because the liquid crystal can be driven efficiently, and thespace between the driving electrode 5 and the opposite electrode 6 canbe widened.

Embodiment 4

[0078]FIGS. 31a and 31 b show the construction of one pixel electrode ofthe liquid crystal displaying apparatus of Embodiment 4 of the presentinvention. FIG. 31a is its plain view. FIG. 31b is a sectional viewtaken along a line of A-A of FIG. 31a. Referring to the drawing,reference numeral 1 denotes a glass substrate, numeral 2 denotes ascanning line, numeral 3 denotes a signal line, numeral 4 denotes a TFT,numeral 5 denotes a driving electrode, numeral 6 denotes an oppositeelectrode, numeral 7 denotes an electrode for forming the storagecapacitance, numeral 8 denotes common line, numeral 9 denotes a gateinsulating film, numeral 10 denotes a passivation film, numeral 11denotes a liquid crystal, numeral 14 denotes a contact hole, numeral 15denotes a source electrode of a TFT 4, and numeral 16 denotes a drainelectrode of the TFT. Numeral 20 denotes an array substrate composing aglass substrate 1, a signal line 3, a driving electrode 5, an oppositeelectrode 6. Numeral 30 denotes an opposite substrate serving as adisplaying picture face arranged opposite to the array substrate 20.Numeral 60 denotes a light shielding film provided on the glasssubstrate 1.

[0079] Embodiment 4 is characterized by formation of a light shieldingfilm 60 on a glass substrate 1, which shields the leakage light from aslit 40 (see FIG. 43a) between the signal line 3 and the oppositeelectrode 6 in the pixel structure of the liquid crystal displayingapparatus of Embodiment 1 through Embodiment 3. The structure of theliquid crystal displaying apparatus of Embodiment 4 will be described inaccordance with FIG. 31a and FIG. 31b.

[0080] A light shielding film 60 is formed on the glass substrate 1 inFIG. 31b. Although not shown in FIG. 31b, the scanning line 2 is alsoformed on the same layer as that of the light shielding film 60. Thescanning line 2 functions as a gate electrode of the TFT 4. A gateinsulating film 9 is laminated on the scanning line 2 and the lightshielding film 60. A signal line 3, in a position superposed on thelight shielding film 60, on the gate insulating :film 9. The TFT 4 isalso formed on the gate insulating Film 9. The TFT 4 can use either ofthe channel etch T FT and the channel passivation film TFT. The sourceelectrode 15 of the TFT 4 and the drain electrode 16 are also formed inthe same layer as that of the signal line 3, so as to laminate thepassivation film 10. Continuously a contact hole 14 is formed in thepassivation film 10. The driving electrode 5 provided on the passivationfilm 10 and the drain electrode of the TFT 4 provided on the gateinsulating film 9 are connected with each other through the contact hole14.

[0081] The opposite electrode 6 is formed on the passivation film 10 asin the driving electrode 5. In a position where the opposite electrode 6is superposed on the light shielding film 60, it is superposed throughthe drain electrode 16 and the passivation film 10 to form the storagecapacitance 7 for keeping the electric potential of the drivingelectrode 5. The opposite electrode 6 is connected with the common line8 provided on the same layer. Broken lines are shown on both the endportions of the pixel of FIG. 31a. The broken lines show a position inFIG. 31a of the light shielding film 60 provided on the glass substrate1 shown in FIG. 31b. As shown by the broken lines, it is found out thata slit 40 (see FIG. 43a) is covered between the signal line 3 and theopposite electrode 6 by formation of the opposite electrodes 6 at boththe ends to be superposed on the light shielding film 60.

[0082] In Embodiment 4, the driving electrode 5 and the oppositeelectrode 6 are formed on the passivation film 10. The driving electrode5 and the signal line 3 are formed simultaneously on the gate insulatingfilm 9 and the opposite electrode 6 can be formed after the passivationfilm has been formed by using silicon nitride or the like. In this case,the driving electrode 5 and the opposite electrode 6 are formed in adifferent layer. In Embodiment 4, the light leaking from the slit 40(not shown) between the signal line 3 and the opposite electrode 6 isnot caused by formation of the light shielding film 60 on the glasssubstrate 1. Thus, the width of the BM 12 of the opposite substrate 30can be made narrower and the light shielding in the direction of thesignal line 3 do not have to be conducted by the BM 12. Therefore, theBM 12 can be omitted so that the opening portion can be provided larger.

[0083] The liquid crystal displaying apparatus is manufactured b-ysuperposed combination between the TFT array substrate and the oppositesubstrate with a color filter attached to it, including the liquidcrystal 11 into between these substrates, and connecting the drivingcircuit. Superposed errors are sometimes caused by a step of superposingthe TFT array substrate and the opposed substrate. Thus, in the BM, thelight shielding area has to be provided larger (see FIG. 43a),considering the superposed errors, so as to positively shield theleakage light from the slit 40 of the TFT array substrate 20. Thetransmission portion of the slit leakage light can be shielded in lightpositively by provision of the light shielding film 60 on the TFT arraysubstrate 20. The superposed error between the TFT array substrate andthe opposite substrate is not necessary to be considered. Thus, the BM12 can be provided into the size of a necessary minimum, and thereby theopening portion can be made larger.

[0084] In the IPS liquid crystal displaying apparatus of Embodiment 4,the driving electrode 5 and the opposite electrode 6 are provided in alayer close to the liquid crystal as in the IPS liquid crystaldisplaying apparatus of Embodiment 1. The liquid crystal can be driveneffectively and the space between the electrodes can be widened, with aneffect of improving the aperture ratio.

Embodiment 5

[0085] A construction of one pixel of the IPS liquid crystal displayingapparatus of Embodiment 5 is depicted in FIGS. 32a and 32 b. The plainview thereof is depicted in FIG. 32a. FIG. 32b is a sectional view takenalong a line A-A of FIG. 32a. Referring to the drawing, referencenumeral 1 denotes a glass substrate, numeral 2 denotes a scanning line,numeral 3 denotes a signal line, numeral 4 denotes a thin filmtransistor (TFT), numeral 5 denotes a driving electrode, numeral 6denotes an opposite electrode, numeral 7 denotes an electrode forforming the storage capacitance, numeral 8 denotes common line, numeral9 denotes a gate insulating film, numeral 10 denotes a passivation film,numeral 11 denotes a liquid crystal, numeral 12 denotes a BM, numeral 14denotes a contact hole, numeral 15 denotes a source electrode of atransistor, and numeral 16 denotes a drain electrode of a transistor.Numeral 20 denotes an array substrate comprising glass substrate 1, asignal line 3, a driving electrode 5, an opposite electrode 6. Numeral30 denotes an opposite substrate serving as a displaying picture facearranged opposite to the array substrate 20.

[0086] Embodiment 5 is characterized by formation of the drivingelectrode 5 and the opposite electrode 6, as in Embodiment 1, in a layerupper than the signal line 3, and furthermore, the formation of theopposite electrode 6 to cover the signal line 3, so as to make it hardto receive the influences of the leakage electric field from the signalline 3 but further, not to cause the leakage light from the slit 40 (seeFIG. 43a) between the signal line 3 and the opposite electrode 6. FIG.33 depicts the simulated results of changes in electric potential causedbetween the driving electrode 5 formed to cover the signal line 3 andthese opposite electrode 6 formed in the same layer as that of thedriving electrode 5. FIG. 33 is the calculated electric potential in thewindow upper portion or lower portion when a white window has beendisplayed on the half tone of 50% in relative transmission factor.

[0087] Between FIG. 46 and FIG. 33 there is shown the electric potentialdistribution in the TFT array substrate of the conventional IPS liquidcrystal displaying apparatus having the driving electrode 5 and theopposite electrode 6 in the layer lower than the signal line 3. In FIG.33, the electric field to be caused by the electric potential differencebetween the signal line 3 and the opposite electrode 6 is shielded bythe opposite electrode 6 arranged on the upper portion to cover thesignal line 3. Thus, the electric potential distribution isapproximately symmetrical in the area close to the signal line 3 of theopening 50 and the area separated from the signal line 3.

[0088] In this manner, the TFT array substrate 20 of the IPS liquidcrystal displaying apparatus of Embodiment 5 can reduce remarkably theinfluences, of the electric field to be caused between the signal line 3and the opposite electrode 6, with respect to the electric field to becaused between the driving electrode 5 and the opposite electrode 6 byformation of the driving electrode 5 and the opposite electrode 6 in alayer upper than the signal line 3, and formation of the oppositeelectrode 6 to cover the signal line 3. The opposite electrode 6 of theend of the opening 50 can be made much closer to the signal line 3, thusmaking it possible to widen the total area of the opening 50 wider.

[0089] As the opposite electrode 6 is formed to cover the signal line 3,the leakage light can be shield, thus making it possible to remove theBM 12. As the area of the opening portion 50 can be widened, a liquidcrystal displaying apparatus higher in brilliance can be provided. As astep of providing the BM 12 can be reduced, the productivity can beimproved, and a liquid crystal displaying apparatus can be produced withlower cost. As in Embodiment 1, the driving electrode 5 and the oppositeelectrode 6 can be formed in a layer close to the liquid crystal. Theliquid crystal can be driven efficiently and the space between theelectrodes can be widened, thus improving the aperture ratio.

Embodiment 6

[0090]FIGS. 34a and 34 b show the construction of one pixel of the IPSliquid crystal displaying apparatus of Embodiment 6. FIG. 34a is itsplain view. FIG. 34b is a sectional view taken along a line of A-A ofFIG. 34a. The construction of the pixel of the IPS liquid crystaldisplaying apparatus of Embodiment 6 shown in FIGS. 34a and 34 b arefundamentally similar to that of the pixel of the IPS displayingapparatus of Embodiment 5 shown in FIG. 12, the description thereof isomitted. Although the opposite electrode 6 of the construction forcompletely covering the signal line 3 is provided in Embodiment 5, theopposite electrode 6 of the construction for covering one portion of thesignal line 3 can be used as in the opposite electrode 6 of the pixel ofthe IPS liquid crystal displaying apparatus of Embodiment 6 shown inFIGS. 34a and 34 b.

[0091] According to Embodiment 6, the opposite electrode 6 is adapted toform one portion of the signal line 3. Thus, the electric field forgenerating the electric potential difference between the signal line 3and the opposite electrode 6 can reduce the influences for influencingthe electric field between the driving electrode 5 and the oppositeelectrode 6, and the leakage light passing through the slit 40 betweenthe signal line 3 and the opposite electrode 6 can be shielded. It ispossible to make the width of the BM 12 narrower or remove the BM 12. Aliquid crystal displaying apparatus which is wider in an opening andhigher in luminance can be realized. Also, a process of providing the BM12 can be reduced by removing the BM 12, so as to improve theproductivity. As a superposed area of the signal line 3 and the oppositeelectrode 6 becomes smaller, the short-circuit defect between the signalline 3 and the opposite electrode 6 can be reduced. As the superposedarea of the signal line 3 and the opposite electrode 6 becomes smaller,the capacitance between the signal line 3 and the opposite electrode 6can be made smaller, so that the load of the wiring can be reduced,making it easier to do a driving operation.

Embodiment 7

[0092]FIGS. 35a and 35 b show the construction of one pixel of the IPSliquid crystal displaying apparatus of Embodiment 7. FIG. 35a is itsplain view. FIG. 35b is a sectional view taken along a line of A-A ofFIG. 35a. As the construction of the pixel of the IPS liquid crystaldisplaying apparatus of Embodiment 7 shown in FIGS. 35a and 35 b arefundamentally similar to that of the pixel of the IPS type displayingapparatus of the embodiment 5 shown in FIGS. 34a and 34 b, thedescription thereof is omitted. Embodiment 7 is characterized byenlarging the opposite electrode 6 up to above the scanning line 2, andconnecting the opposite electrode 6 of the other pixel adjacent to thepixel by using the opposite electrode 6, in the pixel construction ofthe liquid crystal displaying apparatus in, for example, Embodiment 6 asshown in FIGS. 34a and 34 b.

[0093] By using such a construction, the width of the opposite electrode6 becomes thicker so that the resistivity of the opposite electrode 6 islowered and the load is reduced, making it easier to conduct a drivingoperation. As the electric potential is supplied from the oppositeelectrode 6 on the scanning line 2 even when the common line 3 isdisconnected, it does not become defective on display. The reliabilityof the product is improved. The construction of the opposite electrode 6in Embodiment 7 can be adapted to not only to Embodiment 7, but also theother embodiments.

Embodiment 8

[0094]FIG. 36 shows the sectional construction of the storagecapacitance portion of one pixel of the liquid crystal displayingapparatus of Embodiment 8 of the present invention. Referring to thedrawing, reference numeral 17 denotes an electrode for increasing thestorage capacitance formed on the glass substrate 1. Numeral 16 denotesa drain electrode of the TFT. The storage capacitance portion of theliquid crystal liquid displaying apparatus of Embodiment 8 as shown inthe drawing is superposed and laminated on a layer (for example, thelayer of the scanning line 2) separate from the drain electrode 16 ofthe TFT through the gate insulating film 9. It can make the area of theelectrode for forming the storage capacitance smaller by the laminatingconstruction of the electrode of the storage capacitance portion. As aresult, the opening 50 (not shown) of the pixel can be made wider.

Embodiment 9

[0095]FIGS. 37a, 37 b, 38 a, 38 b, 39 a, 39 b, 40 a, 40 b, 41 a, 41 b,42 a and 42 b are views showing the process flow of the TFT arraysubstrate of the Embodiment 9. Referring to FIGS. 37a, 37 b, 38 a, 38 b,39 a, 39 b, 40 a, 40 b, 41 a, 41 b, 42 a and 42 b, reference numeral 1denotes a glass substrate, numeral 2 denotes a scanning line, numeral 3is a signal line, numeral 4 denotes a TFT, numeral 5 denotes a drivingelectrode, numeral 6 denotes an opposite electrode, numeral 8 denotescommon line, numeral 9 denotes a gate insulating film, numeral 10denotes a passivation film, numeral 14 denotes a contact hole, numeral15 denotes a source electrode of a transistor, and numeral 16 denotes adrain electrode of a transistor. Numeral 19 denotes a second passivationfilm. Numeral 20 denotes an array substrate comprising a glass substrate1, a signal line 3, a driving electrode 5, an opposite electrode 6.

[0096] In Embodiment 9, a second passivation film 19 is formed on theTFT array substrate shown in FIGS. 4a through 18 a and FIGS. 4b through18 b. The construction of one pixel of the liquid crystal displayingapparatus of Embodiment 9 is similar to Embodiment 1. A method ofmanufacturing the liquid crystal displaying apparatus of the embodimentwill be described hereinafter. The process flow of the TFT arraysubstrate in Embodiment 9 is similar to Embodiment 1 up to a step forforming the opposite electrode 6. In Embodiment 9, a second passivationfilm 19 is formed on the top layer of the opposite electrode 6.

[0097] By forming the second passivation film 19 between the drivingelectrode 5 and the opposite electrode 6, the short circuit, between thedriving electrode 5 and the opposite electrode 6, due to foreignmaterials can be prevented to improve the yield. As the level differencebetween the driving electrode 5 and the opposite electrode 6 can be madeflat, a high quality of liquid crystal displaying apparatus can berealized where the rubbing treatment necessary for the liquid crystalorientation is equally applied and is less in orientation disturbing.

[0098] According to the IPS liquid crystal displaying apparatus of thepresent invention, the driving electrode and the opposite electrode areformed in a layer close to the liquid crystal different to the signalline. The driving electrode and the opposite electrode are formed in alayer close to the liquid crystal so that the liquid crystal can bedriven more efficiently. Thus, the space between the driving electrodeand the opposite electrode can be widened, so as to improve the apertureratio.

[0099] According to the IPS liquid crystal displaying apparatus of thepresent invention, at least the opposite electrode of the drivingelectrode and the opposite electrode is formed in a layer close to theliquid crystal different from a layer where the signal line is formed,so that influences given by the electric field to be caused by theelectric potential difference between the signal line and the oppositeelectrode.

[0100] According to the IPS liquid crystal displaying apparatus of thepresent invention, the opposite electrode is formed to cover one portionor all the portion of the signal line. The electric field to be causedby the electric potential difference between the signal line and theopposite electrode influences the electric field to be caused betweenthe driving electrode of the opening and the opposite electrode, therebyrestraining a problem of deteriorating the picture quality on thedisplaying from being caused. Thus, the liquid crystal display of highpicture quality can be made and the leakage light from between thesignal line for making the black light a light source, and the oppositeelectrode can be shielded accurately. The BM can be removed, so as toimprove the aperture ratio.

[0101] According to the IPS liquid crystal displaying apparatus of thepresent invention, at least the opposite electrode is provided in alayer different from the scanning line so as to cover one portion or allthe portion of the scanning line. The opposite electrode of the otherpixel can be connected by the opposite electrode, so that the width ofthe opposite electrode can be made thicker without reduction in the areaof the opening. Accordingly, the resistivity of the opposite electrodecan be lowered to reduce the load of the wiring. As the electricpotential can be fed from the opposite electrode on the scanning linewhen the common line is disconnected, the reliability can be increasedby restraining the defects on the displaying from being caused.

[0102] According to the IPS liquid crystal displaying apparatus of thepresent invention, the common line and the scanning line are provided onthe same layer and the single line is provided on a layer closer to theopposite substrate than to the common line and the scanning line. Thedefect to be caused in the stage difference portion can be restrained.

[0103] According to the IPS liquid crystal apparatus of the presentinvention, a passivation film which formed approximately flat in surfacewhere the TFT array substrate comes into contact with the liquidcrystal. Thus, the gap between the array substrate surface and theopposite substrate across all the display picture surface is equallyconstructed with precision. The rubbing treatment necessary for theliquid crystal orientation is equally applied and the orientationdisturbing can be reduced. The liquid crystal displaying apparatus whichis less in uneven luminance across the whole picture face can berealized. The fraction defective which is caused by cracks in the stagedifference portion of the passivation film becomes smaller, so as toimprove the yield.

[0104] In the IPS liquid crystal displaying apparatus of the presentinvention, a TFT array substrate is provided having a light shieldingmeans formed to have the signal line and the opposite electrodesuperposed. The leakage light for transmitting through the slit can beshielded, and thus the BM provided on the opposite substrate becomesunnecessary. The superposed errors are not necessary to be considered inthe superposition between the TFT array substrate and the oppositesubstrate in determining the size of the light shielding means. Thus,the size of the light shielding means can be made that of a necessaryminimum, so as to improve the aperture ratio.

[0105] According to the in plain switching type liquid crystaldisplaying apparatus of the present invention, a TFT array substrateformed to be superposed with a TFT, a driving electrode, and a storagecapacitance increasing electrode being different in layer. The area ofthe electrode for forming the storage capacitance can be made smallerand the opening portion of the pixel can be made wider correspondingly,and the liquid crystal displaying apparatus higher in luminance can berealized.

[0106] Though several embodiments of the present invention are describedabove, it is to be understood that the present invention is not limitedonly to the above-mentioned, various changes and modifications may bemade in the invention without departing from the spirit and scopethereof.

What we claim is:
 1. An IPS liquid crystal displaying apparatus comprising: a TFT array substrate, an opposite substrate opposed to said TFT array substrate and liquid crystal interposed between said TFT array substrate and said opposite substrate, wherein said TFT array substrate is composed of a glass substrate, a gate insulating film formed on said glass substrate, a passivation film formed on said gate insulating film, a plurality of scanning lines for transmitting a scanning signal, said plurality of scanning lines being formed on said glass substrate, a plurality of signal lines for transmitting an image signal, said plurality of signal lines being formed on said gate insulating film, a plurality of pixels arranged in grid like pattern by crossing said plurality of scanning lines with said plurality of signal lines, a plurality of TFTs implementing switching operation of said image signal on basis of said scanning signals, a plurality of driving electrodes connected with said TFT, a plurality of opposite electrodes arranged in such a manner that each of said plurality of opposite electrodes is opposed to each of said driving electrodes, and a plurality of common lines for mutually connecting each of said opposite electrode of one of said plurality of pixels with other one of said plurality of pixels, wherein said TFT array substrate is formed on said passivation film, said passivation film being different from a layer provided with said driving electrode and said opposite electrode.
 2. The IPS liquid crystal displaying apparatus of claim 1 , wherein said TFT array substrate is provided with a driving electrode for driving said liquid crystal layer by causing electric field parallel to said TFT array substrate face, and an opposite electrode connected with a common line, and said TFT array substrate is provided with at least said opposite electrode formed on said passivation film, different from a layer where said signal line is formed.
 3. The IPS liquid crystal displaying apparatus of claim 2 , wherein said TFT substrate is provided with said opposite electrode formed to cover one portion of said signal line or all portion of said signal line.
 4. The IPS liquid crystal displaying apparatus of claim 3 , wherein said TFT array substrate is provided with said opposite electrode formed to cover one portion of said scanning line or all portion thereof, at least said opposite electrode being provided in a layer different from said scanning line.
 5. The IPS liquid crystal displaying apparatus of claim 1 , wherein said TFT array substrate is provided with a common line and a scanning line on a same layer, and a signal line provided on said gate insulating film.
 6. The IPS liquid crystal displaying apparatus of claim 1 , wherein said TFT array substrate is provided with a passivation film, a surface of which is approximately flat in shape.
 7. The IPS liquid crystal displaying apparatus of claim 1 , wherein said TFT array substrate is provided with a light shielding means formed in such a manner that said signal line is superposed with said opposite electrode.
 8. The IPS liquid crystal displaying apparatus of claim 1 , wherein said TFT array substrate is formed in such a manner that a TFT for switching said image signal in accordance with said scanning signal, a driving electrode for accumulating while switch of said TFT is off electric load stored when said switch of said TFT is on, and a storage capacity increasing electrode for reinforcing the accumulating force of said driving electrode are respectively superposed in different layer. 